Method and apparatus for making corrugated containers of longitudinally corrugated strips on continuous basis

ABSTRACT

The present invention relates to a method and apparatus for making corrugated cardboard container blanks of longitudinally corrugated cardboard based on a new idea of producing stitchless corrugated container blanks on a continuous basis. An elongated strip of corrugated cardboard is formed, the corrugations of the core ply of which extend longitudinally. The face plies are laterally offset in opposite directions so as to form stepped edges at both sides of the strip. Transverse and longitudinal folds or creases and slots are formed in the strip and the strip is formed into a tube by joining the stepped edges on a mandrel which is gradually flattened, and individual stitchless corrugated container blanks can then be cut off the flattened tube.

United States Patent [191 1111 3,838,632

Miyake Oct. 1, 1974 [5 METHOD AND APPARATUS FOR MAKING 3,444,792 5/l969Thesing et al 93/82 x CORRUGATED CONTAINERS .OF 3,732,790

LONGITUDINALLY CORRUGATED STRIPS ON CONTINUOUS BASIS Inventor: HajimeMiyake, Osaka, Japan Assignee: Kabushiki Kaisha, Osaka, Japan Filed:Aug. 14, 1972- Appl. No.: 280,210

US. Cl. 93/94 PS, 93/36 R, 93/82 Int. Cl B3lb 17/74 Field of Search93/94 PS, 94 R, 82, 36 R,

I 93/36 MM References Cited UNITED STATES PATENTS 7/l959 Mann 93/94 R4/1960 Molla 93/94 R 6/1964 Elliott 93/94 PS 5/1973 Miyake et al. 93/94R Primary ExaminerRoy Lake Assistant Examiner.lames F. Coan Attorney,Agent, or Firm-Wenderoth, Lind & Ponack [5 7 ABSTRACT The presentinvention relates to a method and apparatus for making corrugatedcardboard container blanks of longitudinally corrugated cardboard basedon a new idea of producing stitchless corrugated container blanks on acontinuous basis. An elongated strip of corrugated cardboard is formed,the corrugations of the core ply of which extend longitudinally. Theface plies are laterally ofi'set in opposite directions so as to formstepped edges at both sides of the strip. Transverse and longitudinalfolds or creases and slots are formed in the strip and the strip isformed into a tube by joining the stepped edges on a mandrel which isgradually flattened, and individual stitchless corrugated containerblanks can then be cut off the flattened tube.

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METHOD AND APPARATUS FOR MAKING CORRUGATED CONTAINERS OF LONGITUDINALLYCORRUGATED STRIPS ON CONTINUOUS BASIS This invention relates to a methodof making corrugated container blanks, more particularly to anintegrated method of making so-called longitudinally corrugated stripsstrips in which the flutes of the core ply extend in the longitudinaldirection of the strip and making flat folded corrugated containerblanks therefrom and a manufacturing apparatus for the above integratedmethod.

In the prior art of making so-called transversely corrugated cardboardstrips as shown in FIG. 36 a, flutes are formed at right angles to thedirection of elongation of the strip which is conventional in thepresent technique of corrugated cardboard making. This involves spoilingof the paper fiber and finished containers of such cardboard do not havesufficient strength because the direction of the fibers in thecorrugated core ply and face plies superposed thereon are at a rightangle with the top-to-bottom direction of a container. In the process ofmaking corrugated cardboard containers, joining of the ends of thecorrugated cardboard strip is effected by either stitching or pasting.In the case of stitching, the joint strength is weak because it ispartial joined and the cardboard is damaged by the stitching. On theother hand, where only the surface of an outer face ply and an innerface ply of the container are pasted together, with the corrugated coreply left unpasted, such a joint is easy to split. Thus the joint hasbeen the weakest portion of the conventional corru gated container.

Furthermore, in the prior method of making corrugated containers, atfirst corrugated cardboard of a certain standard size is made and thenparts necessary for making containers are measured and cut out of thecardboard. This involves a large amount of waste. According to the priormethod of making transversely corrugated strips, it was impossible tointegrate the process of manufacturing corrugated cardboard directlywith the process of making corrugated container blanks because thedirection of the core ply flutes at the time of making corrugatedcardboard is at right angles to the direction of the corrugations in thefinished corrugated cardboard containers. In the process of makingcorrugated container blanks, it is necessary to install a singlefunctionmachine for each process, i.e., a slitter, a slotter, a gluer, astitcher, a die cutter, and so on, and corrugated cardboard has to becarried to each machine for processing. This not only requires a largefactory area but also exployment of many workers.

As shown in FIG. 36 b, so-called longitudinally corrugated cardboard hasthe flutes in the core ply parallel with the direction of the paperfiber. This'involves no spoiling of the paper fiber and makes itpossible to utilize the strength in the longitudinal direction which isan essential object of corrugated cardboard, thereby improving thetop-to-bottom compressive strength of corrugated containers to a greatextent. Moreover, if the flutes of the core ply of the corrugatedcardboard are kept in the longitudinal direction, ranging from the firstcorrugating process up to the last container blank making process, it ispossible to mass-produce corrugated container blanks by a continuousprocess using simple apparatuses.

A primary object of the present invention is to provide a method and anapparatus for making flat folded stitchless corrugated container blankson a continuous production basis, by making an elongated strip oflongitudinally corrugated cardboard, making the strip into a tubularbody, and further making the tubular body into stitchless corrugatedcontainer blanks.

Various apparatuses for making longitudinally corrugated cardboard haveso far been devised, for example, a method of feeding a core ply into ashaping disk with the space between teeth narrowed gradually andpressing it by a roller and a method of arranging upper and lowerendless belts in a line with the space therebetween narrowed gradually.However, while the former has such disadvantage that the core ply breakseasily during operation due to the high resistance of such core plies topulling, the latter can cause irregularity in the corrugations due tothe elasticity of belts with resultant irregularity in the quality ofthe finished goods. Due to such disadvantages, these methods have notbeen employed in practice.

With the above in view, studies have been made of a new method of makinglongitudinally corrugated cardboard, based on the principle that a coreply is inserted between groups of rotatably supported balls to be cor:rugated on semicircular contact lines which are formed by contact withthe balls and the freedom in the transverse direction can be obtaineddue to the groups of balls being rotatably supported.

This new method has been developed successfully and has overcome theabove-mentioned disadvantages.

The present invention uses this new method.

Another object of the present invention is to produce corrugatedcontainer blanks having a joint which presents a good appearance inwhich both face plies and a corrugated core ply overlap one anotherproperly and v are well joined.

A further object of the present invention is to provide an economicalmethod in which face plies and a core ply to be corrugated are cut in adesired width at the start of production and are immediately transferredto the edge joining process, thereby eliminating the loss of material.

The nature and advantages of the present invention will be understoodmore clearly from the following description made with reference to theaccompanying drawings, in which:

FIG. 1, parts A-H and El-E4 are diagrams showing processing proceduresat each stage of the process of making a container blank, part (A) beinga transverse cross-sectional view of a longitudinally corrugatedcardboard, parts B, C, D, E, F, G and H being partly sectionalperspective views respectively, and E, through B, being cross sectionalviews illustrating a corrugated cardboard on lines A-A, B-B, H-I-I, E,EE.,E respectively.

FIG. 2 is a perspective view showing a core ply of longitudinallycorrugated cardboard at the position encircled with chain line in FIG.4.

FIG. 3 is a plan view of an apparatus for making corrugated containerblanks continuously, according to the present invention.

FIG. 4 is a side elevation view of the apparatus shown in FIG. 3.

FIG. 5 is a side elevation view of an apparatus for shaping corrugatedstrips according to one embodiment of the present invention.

FIG. 6 is a plan view of the apparatus shown in FIG.

FIG. 7 is a front elevation of corrugation forming rollers of theapparatus of FIG. 5.

FIG; 8 is a sectional view taken along line M-M in FIG. 5.

FIG. 9 is a partial sectional view on an enlarged scale taken along lineJ--.[ in FIG. 5.

FIG. 10 is a partial sectional view on an enlarged scale taken alongline K-K in FIG. 5.

FIG. 11 is a sectional view of a part of FIG. 8, on an enlarged scale.

FIG. 12 is an elevation view,-partly in section and on an enlargedscale, showing a part of the lower ball supporting rod.

FIG. 13 is a plan view of FIG. 12.

FIG. 14 is a sectional view taken along line NN of FIG. 12.

FIG. 15 is a sectional view taken along line 0-0 of FIG. 12.

FIG. 16 is a front elevation view, partly in section, of the device formaking transverse folds or creases.

FIG. 17 is a sectional side view of a main part of the device for makingtransverse folds or creases.

FIG. 18 is a front elevation view, partly in section, of

a main part of the device for making transverse folds or creases.

FIG. l9-is a front elevation view, partly in section, of the device tomake slot.

FIG. 20 is a sectional side viewof a main part of the device to makeslot.

FIG. 21 is a transverse sectional elevation of a main part of the deviceto apply adhesive.

FIG. 22 is a transverse sectional view, on an enlarged scale, showingthe edges of the longitudinally corrugated cardboard.

FIG. 23 is a broken sectional view of the heating device provided in themandrel.

FIG. 24 is a sectional side view of the corrugated board feeding deviceprovided outside the rectangular mandrel.

FIG. 25 is a transverse sectional view of the feeding device shown inFIG. 24.

FIG. 26 is a front view of a main part of the feeding device provided atthe flat part of the mandrel.

FIG. 27 is a sectional side elevation view of the severing device.

FIG. 28 is a transverse sectional .view of a corrugated cardboardtubular body illustrating overlapping of edges.

FIG. 29 is a sectional view, on an enlarged scale, of the part of thebody encircled with chain line in FIG. 28.

FIG. 30 is a sectional view of a corrugated cardboard tubular bodyillustrating overlapping of edges according to another embodiment of thepresent invention.

FIG. 31 is a sectional view, on an enlarged scale, of the part of thebody encircled with chain line in FIG. 30. FIGS. 32a and b aretransversely sectional perspective views, respectively, of alongitudinally corrugated cardboard.

FIG. 33, parts PP are transverse sectional diagrams taken oncorresponding section lines in FIG. 34 to illustrate folding of acorrugated cardboard along the sides of the mandrel.

FIG. 34 is a side elevation view of the device for making longitudinallycorrugated cardobard.

FIG. 35 is a transverse elevation of a main part of the device to applyadhesive. FIGS. 36a and b are perspective diagrams for showing acomparison of corrugated cardboard manufactured process by theconventional method and the method according to the present invention.

The process of producing the flat folded corrugated container blanksaccording to this invention will be explained hereinafter.

FIG. 1 shows a corrugated coardboard 4 comprising face plies 1 and 2which are fed in parallel with each other from mill roll stands andbetween which a corrugated core ply 3,'the corrugations of which extendin the direction of the length of the strip as it moves through themachine is positioned.

The face plies l and 2, and the corrugated core ply 3 have the samewidth. However, the face plies l and 2 are laterally offset in-oppositedirections in such a manner that stepped edges and 7b are formed. Whilethe corrugated cardboard 4 is fed on a supporting plate 16 in thedirection of the arrow I shown in FIG. 1 B,transverse folds or creases18 are applied by a transverse creasing device 46 shown inFlG. 3.Longitudinal folds or creases 19 are applied next by a longitudinalcreasing device 56 as shown in FIG. 3 C. Slots 20 are made on saidlongitudinal folds or creases 19 at regular intervals of length, asshown in heavy lines in FIG. 3 D, by a slotting device 59. Thecorrugated cardboard strip 4 treated according to the above processes isfed onto a mandrel 17 comprising a tubular part 17a to form a tubehaving a rectangular section, an intermediate part 17b which followssaid tubular part and changes gradually into a flat form and a flat part17c. By said mandrel 17, the cardboard is bent downwardly atlongitudinal folds or creases 19b and 190 as shown in FIG. 1 (B Acorrugated tube 5 as shown in FIG. 1 (E) is formed by the cardboardbeing bent at the longitudinal folds or creases 19a and 19d to conformto each face of the mandrel 17 'as shown in FIG. 1 E E and causing theedge 7b to overlap the edge 7a for forming a joint 7c. Said tube 5 is,as shown in FIG. 1 F as it passes along the intermediate part 17b ofsaid mandrel, gradually flattened and after passing over the flatportion 170 of the mandrel, becomes a flat folded tube 6, as shown inFIG. 1 G, which is then severed by a severing device on a severing line139 at the middle of the length of each slot 20, whereby individual flatfolded container blanks are obtained.

A description will now be given of an apparatus to produce the foldedcontainer blanks of thepresent invention.

The plain face plies 1 and 2 are drawn out from mill roll stands 8 and 9respectively, and the face ply 1 then is passed through an adhesiveapplicator roll 11a, 21 support roll 11 and guiding rolls 12a and 12b,and the face ply is passed through an adhesive applicator roll 13a, asupport roll 13b and guiding rolls 12a and 12b. The corrugated core ply3 the corrugations of which are made by a corrugation forming device 23to be described later, is fed by pulling rollers 36 and 37 in thedirection of passage of the elongated cardboard strip and then is passedthrough adhesive applicator rollers 14a and 14c, support rolls 14b and14d and guiding rolls 12a and 12b. The three plies passed through saidguiding rolls are combined on a support plate 16 with the face plies land 2 offset in opposite directions relative to the core ply 3 so thatstepped parts are formed at the edges of strip 4, thereby forming anelongated strip of longitudinally corrugated cardboard 4. Numerals a,15b and 150 designate edge detectors for the face plies and thecorrugated strip. Signals detected by said edge detectors 15a, 15b and15c are transmitted to a support mechanism for said supplies of faceplies l and 2 and the corrugated core ply 3 (not shown in the drawings),comprising an automatic regulating device which adjusts said supportmechanism at right angles to the direction of passage of the strip andfor accurately controlling the size of the stepped edges 7a and 7b whensaid face plies 1 and 2 and said corrugated core ply are combined.

Numeral 21 in FIG. 3 denotes a steam supply device which, when a flatcore ply drawn out from a reel 10, passes therethrough, sprays steamthereon from a nozzle 22 (FIG. 5) so as to humidify said core ply to aconstant degree of moisture content. Numeral 23 denotes a core ply guidemeans (FIG. 5) which passes said core ply L between an upper ballsupporting rod group and a lower ball supporting rod group so that thepitch of the flutes made by said groups becomes gradually smaller.Numeral 24 denotes upper ball supporting rods which are arrangedregularly in a plane and at regular intervals, the space betweenadjacent rods being made gradually narrower in the direction of passageof the strip (arrow 1). Numeral 25 denotes lower ball supporting rods,each of which is arranged below a corresponding upper ball supportingrod. The upper surface of said upper ball supporting rods 24 is securedto fixing means 26a, 26b, 26f and the lower surface of said lower ballsupporting rods 25 is secured to fixing means 27a, 27b, 27f and said twofixing means are supported by legs 28a, 28b and 280. A ball 29 (FIG. 9)made of an abrasion resistant material, such as steel or nylon, isinserted in a conical-shaped groove 30 which is provided at the end ofeach supporting rod 24 and 25, the upper half of said ball 29 being heldby a metallic cover piece 31 fixed to the supporting rods 24 and 25 soas to prevent said ball from slipping off. The fixing means 26a, 26b,26f securing the upper ball supporting rods 25 are provided with afixing piece 32 at both ends thereof which is secured to the side 33 ofsaid fixing means 27a, 27b, 27f by a bolt 34. Numeral 35 denotes acorrugation forming roller which sets corrugations by heating whilepulling the core ply L. Male and female pulling rolls 36 and 37respectively have on the surface thereof flute-shaped grooves meshingwith each other and steam is supplied by a pipe 38 thereto andcondensate is exhausted by a drain pipe 39 secured to a drain pipeinside of said roll. Said pulling rolls 36 and 37 rotate while beingsupported by bearings 40 and 41 and are connected, by a rotatingconnector 42, to said fixed pipe 38 and the drain pipe 39. Numerals 43and 44 denote gears meshing with each other and secured to the shafts ofsaid pulling rolls 36 and 37 and numeral 45 denotes a driving gear.

A description will now be given of the process of forming the core ply Linto a corrugated core ply 3. The core ply L passed through the steamsupply device 21 is inserted between balls 29 carried by the uppersupporting rods 24 and the lower supporting rods 25 as illustrated inFIG. 9 showing a section at the position J-J of FIG. 6 so as to becorrugated. The space between the supporting rods 24 and 25 is madenarrower in the direction of movement of.the ply so that as the core plyL proceeds forward, the pitch P of the flutes becomes gradually smaller,the pitch P of the flutes at the foremost position M-M being as shown inFIG. 11. The corrugated core ply L having such pitch of the flutes ispulled as it is sandwiched between grooves of the corrugation formingroller 35 and the corrugations are set by the heated pulling rolls 36and 37 to such a degree that they are free from deformation. By theabove-mentioned process, the core ply L is continuously fed from thecorrugation forming roller 35 in the form a longitudinally corrugatedply 3 as shown in FIG. 3.

Numeral 16 denotes a flat supporting plate the terminal end (left-handof FIG. 3) of which comes close to the mandrel 17, and which is held bylegs 138. This plate supports the corrugated cardboard strip 4horizontally thereon and passes said cardboard 4 through the processesof transverse creasing, longitudinal creasing, slotting and the like.

A creasing roll 48 of a device 46 for making transverse folds or creases(FIG. 16 and FIG. 17) is supported by a shaft 50 by means of a spring 49provided at both ends of said roll and is attached rotatably to abracket which is fixed to a support. A gear 51 is provided at one end ofsaid shaft 50. By a gear meshing with said gear 51, power from a motor53 is transmitted to the creasing rolls 48 by means of a reduction gear54. Provided on the surface of the creasing roll is a blade 55 whichcompresses the corrugated cardboard 4 between itself and the supportingplate 16 during the rotation of the creasing roll, thereby formingtransverse folds or creases 18. Since the corrugated board 4 is pulledat a constant speed, if the diameter and the r.p.m. of the creasing roll48 are properly designed and adjusted (adjustment of the r.p.m. is madeby means of the reduction gear 54), the size of the finished goods orfolded container blanks 150 can be changed as desired. For this purpose,several-step change gears are preferably provided in the reduction gear54. The transverse creasing device is driven by a separate motor in theexample of FIG. 16', however, the transverse creasing, as describedlater, has a close relation with the slotting process and the severingprocess so that if a transverse creasing device, a slotting device andsevering device are driven synchronously, irregularities which mightoccur in each process can be avoided.

A device 56 (FIG. 18) is provided to make longitudinal folds or creasescontinuously in the corrugated board 4 for enabling it to be formed intoa tube by lapping the corrugated board 4 about the mandrel 17. A shaft58 to which four disks 57 having sharp circumferential edge are fastenedat regular intervals can be supported rotatably in bearings at both endsthereof and be connected to a motor for rotation. The interval betweendisks 57 can be changed, depending on the desired container shape.

A device 59 (FIG. 19, FIG. 20) is provided to make slots intermittentlyin longitudinally creased parts of the corrugated board and comprisesfour disks 62 on a shaft 61 supported rotatably on a bracket 60, androtatable blades 63 secured to said disks. Openings 65 are provided in abase 64 through which grooved slotting rolls 66 rotatably fixed to ashaft 67 are exposed opposite the respective rotating blades 63. A gear68 is provided at one end of the shaft 61, to which gear power istransmitted from a motor 70 through a reduction gear 71 and a gear 72.

A device 73 is, as shown in FIG. 21, provided to apply adhesive to bothstepped edge portions 7a and 7b of the corrugated board 4. A steppedadhesive applicator roll 74 which conforms to the stepped form of theedge portions 7a and 7b of the corrugated cardboard 4, is arrangedopposite a supporting roll 75 and both rolls are driven by a suitablepower means. The corrugated cardboard 4 is fed between these rolls sothat adhesive is continuously applied thereto by the adhesive applicator74. To this adhesive applicator, an adhesive tank, a doctor roll, acleaning roll (none of which are shown) and the like are associated withthe rolls so that pasting is effected uniformly. The detailedexplanation of this device is omitted here since it is conventional.

The mandrel 17 has the corrugated cardboard 4 folded around the outersurface thereof to form a tube. The cross-section of the mandrel 17supported and fixed by a leg 76 as shown in FIG. 3 is rectangular atlines E,-E,, E E E-E, is elliptical on line FF and substantially aroundline GG.

Around the mandrel are provided levelling rollers 77a, 77b, 77c, 79a,79b, 81a and 81b at the upper and lower sides thereof and levellingrollers 78a, 78b, 80a, 80b at the sides thereof, respectively, to shapethe corrugated cardboard 4 to the mandrel 17. Following these levellingrollers in the direction of movement of the tube is a pressing roller 83which presses the overlapped edge portions 7a and 7b of the corrugatedcardboard 4 together thereby forming a corrugated tube 5. At thepressing roller section, heat is applied to dry the overlapped edges oftube 5. As a heating means, an electrothermic or the steam type heateris most preferable, and steam heating apparatus as shown by 84 in FIG.23 is disclosed for the embodiment of the present invention. A steamsupplying pipe 85, which has a helical portion 88 in the mandrel and hasa drain pipe 89, is connected at one end 86 to a steam generator (notshown in the drawings).

A device 91 (FIG. 24, FIG. 25) is provided to feed the corrugatedcardboard 4 and the tube continuously and is provided near the pressingroller 83at the portion where the corrugated cardboard 4 is finishedinto a tube at the end of the mandrel.

The device has four driving elements, one on each face of the mandrel,and each comprising a driving roller 95 rotatably mounted on asupporting shaft 94 which is fixed to a support 93 and a driven roller97 is rotatably mounted on a supporting shaft 96, and an magneticendless belt 98 extending between said driving roller and said drivenroller and stretched outwardly by means of a tension roller 100. Thetension of the endless belt 98 is adjusted by an adjusting bolt 101which is connected to said shaft 96. The driving roller 95 of eachdriving element is connected to the other driving rollers by means of abevel gear 102 and bevel gear 109 connects one bevel gear 102 to a motor103 for driving the driving rollers simultaneously.

A feeding device 120 is provided at the flat portion of the mandrel 17shown in FIG. 3 and FIG. 4 on the line 6-6. Fixed to roller shafts 122and 123 which are rotatably supported on a bracket 121, are feedingrollers 124 and 125 which have a non'skid surface (for example, acoating of rubber or the like) on the surfacegears 126 and 127 havingthe same pitch for rotating both feeding rollers at the same speed.

A severing device 130 shown in FIG. 27 is provided to sever from thefolded corrugated tube 6 cardboard container blanks of uniform length.Fixed to a stud 131 are two guiding plates 132 on each of which asevering knife 133 is slidably mounted within a groove 134. The severingknives are constantly urged to move outwardly by springs 135a aroundarmatures of solenoid l35, the armatures being connected to armsprojecting fromthe ends of the severing knives 133. Upon energization ofsaid solenoid, the severing knives 133 are drawn toward each other andthe blade 136 thereof cooperate to sever from the folded tube 6 flatfolded cardboard blanks of uniform length, which are fed to a stackingdevice 140.

A stacking device 140 (FIG. 3, FIG. 4) stacks and sends the foldedcardboard blanks to be packed.

A description of the method of overlapping the edge portions 70 and 7bof the corrugated cardboard will now be given. Methods of overlappingthe corrugated strip 3 and of abutting it are shown in FIG. 28 and FIG.29, and in FIG. 30 and FIG. 31, respectively. In the former, the edgesof the corrugated core ply 3 and'the face plies 1 and 2 superposedthereon to form the stepped edges are each overlapped. The edges of thecorrugated strip 3 are overlapped in such a fashion that a convexportion of one flute is overlapped by the convex portion of anotherflute and a concave portion of one by a concave portion of another. Forthat purpose, adhesive is applied to the edge portions 7a and 7b asshown in FIG. 20. In the latter case, the face plies are overlapped butthe corrugated ply 3 has the edges abutted.

The apparatus for forming a corrugated tube 5 from one sheet of doublefaced corrugated cardboard 4 has been described hereinbefore but asimilar corrugated tube can be made from two strips of corrugatedcardboard, each of which is bent and then secured to the other. Thisembodiment isshown in FIG. 32 FIG. 35, especially the different featuresfrom those in the first described embodiment.

In this embodiment two sets of the devices up to the guiding rollers 12aand 12b on the mandrel shown in FIG. 3 and FIG. 4, are provided forforming corrugated cardboard strips 141 and 1142 which are one half thewidth of the corrugated cardboard 4 by superposing face plies l and 2and a longitudinally corrugated core ply 3.

The corrugated strips 141 and 142 are fed to an apparatus for makingflat folded blanks for box-shaped containers which comprises a series ofdevices, i.e., a transverse creasing device, a longitudinal creasingdevice, a slotting device, a feeding device, a folding and overlappingdevice and a severing device.

These devices are the same as those in the first embodiment, except thattwo sets of the transverse creasing device, the longitudinal creasingdevice and the slotting device are provided, one above and one below themandrel, so that a detailed description thereof is omitted here. Thecorrugated strips 141 and 142, after having longitudinal creases 19b andand a slot 20 formed therein, are fed to an adhesive applying device 167at the same time. In this device, which different from the that earlierdescribed embodiment, the stepped edge portion 7a and 7b of both stripsare each continuously coated by means of an adhesive applying roller 190and a support roller 191 as shown in FIG. '33 and after that thecorrugated strips 141 and 142 are fed to the mandrel 17. The adhesivecoated corrugated strips 141 and 142 are folded and overlapped at theedges in the steps shown in parts P P P P of FIG. 33. The centralportion of each corrugated strip 141 and 142 between the longitudinalcreases 19b and -19c is placed in contact with the respective upper andlower faces of the mandrel 17 and leveling rollers 170, 171, 172 and 173provided along the mandrel 17, fold portions 143 and 146 of thecorrugated strips 141 into close contact with the mandrel l7, and thenfold portions 144 and 145 against the mandrel. By this method, acorrugated tube 147 is formed with the edge 143 of the corrugated strip141 being overlapped by the edge 145 of the corrugated strip 142 and theedge 146 being overlapped by the edge 144. As can be seen from thesection of said tube in FIG. 30, two edge overlapping portions 148a and148b are formed. The thus formed tube 147 is pressed by pressing rollers174, 175, 176a, 176b, 177, 178a and 178 b, is fed forward and is heatedand dried by a heater in the mandrel, is .gradually flattened, and issevered in the desired lengths by a severing device, whereby foldedcorrugated blanks for boxshape containers are formed and said blanks arefed to a stacking device. By these devices, box-shape folded cardboardcontainers 200 are made continuously from one corrugated board. Numerals160 and 161 in FIG. 34 denote upper and lower support platesrespectively, numerals 162 and 163 denote guiding rollers, numeral 164denotes a transverse creasing device, numeral 166 is a slotting device,numeral 167 is an adhesive applying device, numerals 168a and 168b aresupport rollers, and parts P P P and P of FIG. 33 are sections on.

lines -P P P -P P P and P'P in FIG. 34 respectively.

There has been described a method and an apparatus for making flatfolded blanks for corrugated containers continuously from alongitudinally extending corrugated cardboard strip which is made bycontinuously superposing between face plies on a longitudinallycorrugated strip. However, flat folded blanks for rectangularcross-section tubular containers can also be made by omitting thetransverse creasing step and the slotting step. By increasing the numberof creases and by changing the cross-sectional shape of the mandrel l7,hexagonal-, octagonaland tubular-shape folded corrugated cardboardcontainers can also be made. Recently the market demand for foldedcorrugated containers is overwhelmingly for rectangular cartons. As thethermal drying conditions are the most important element formanufacturing corrugated cardboard having well adhered corrugations on ahigh speed manufacturing basis, a dryer using infrared rays or heatedair can be provided at the position 300 in FIG. 4, so as to compensatefor loss of heat instantly and thereby minimize the decrease intemperature.

The present invention is, as above described, a method and apparatus formanufacturing folded corrugated cardboard which undergoes processeswhich form it into a tube, which is made gradually flat and severed intoindividual containers, whereby containers of a certain size which aretough and fit for packing oranges, eggs or vegetables can bemanufactured efficiently on a continuous processing and mass productionbasis.

The method and apparatus according to the present invention, therefore,have the following various advantages; v

l. The apparatus can be made compact in size and in one unit, sincecontinuous operation is possible.

2. The cost for installing the manufacturing apparatus and the laborcost for operating the same are very small.

3. The material loss is reduced to nearly zero and inexpensivecorrugated containers can be obtained.

4. Corrugated box-shape containers having a large compressive strengthcan be obtained.

5. Corrugated containers having excellent joint strength are producedcomprising face plies and a corrugated core ply which are superposed onone another and are overlapped completely at each edge thereof.

6. In the manufacturing apparatus, the device for feeding can bemadesimple, taking advantage of the fact that corrugations are formed in thedirection of passage of the strip through the machine so that the stripis strong in said direction when it is fed on the support plate and onthe mandrel.

We claim:

1. A method of continuously producing flat folded corrugated containerblanks, comprising the steps of:

making an elongated strip of corrugated cardboard having a corrugatedcore ply the corrugations of which extend longitudinally thereof andhaving face plies on the opposite faces of said core ply with one faceply laterally offset in one direction relative to the core ply and theother face ply laterally offset in the opposite direction relative tothe core ply;

moving said strip of corrugated cardboard longitudinally along anelongated mandrel and folding the strip around the mandrel to form atube of the corrugated cardboard in which the corrugations of the coreply extend in the direction of the length of the tube, and adhering theedges of the offset face plies and the edges of the core plies to eachother; flattening said tube; and

severing the flattened tube into desired lengths.

2. A method as claimed in claim 1 further comprising the steps ofcreasing, scoring and slotting said flattened tube for forming cartonblanks from the said lengths.

3. A method as claimed in claim 1 in which the step of adhering theedges of the offset plies and the edges of the core plies comprisesadhering the inner surface of the edge of each face ply which projectsbeyond the core ply to the outer surface of the edge of said face plybeyond which the core ply extends.

4. A method as claimed in claim 3 in which the corrugations at one edgeof the core ply are interfitted with the corrugations at the other edgeof the core ply.

5. A method as claimed in claim 3 in which the corrugation at one edgeof the core ply is abutted against the corrugation at the other edge ofthe core ply.

6. An apparatus for producing flat folded corrugated container blanks,comprising:

a corrugating means for receiving a strip of flat core ply stock andforming in it corrugations extending longitudinally of the strip to forma strip of core P y; a support plate for receiving the strip of coreply;

1. A method of continuously producing flat folded corrugated containerblanks, comprising the steps of: making an elongated strip of corrugatedcardboard having a corrugated core ply the corrugations of which extendlongitudinally thereof and having face plies on the opposite faces ofsaid core ply with one face ply laterally offset in one directionrelative to the core ply and the other face ply laterally offset in theopposite direction relative to the core ply; moving said strip ofcorrugated cardboard longitudinally along an elongated mandrel andfolding the strip around the mandrel to form a tube of the corrugatedcardboard in which the corrugations of the core ply extend in thedirection of the length of the tube, and adhering the edges of theoffset face plies and the edges of the core plies to each other;flattening said tube; and severing the flattened tube into desiredlengths.
 2. A method as claimed in claim 1 further comprising the stepsof creasing, scoring and slotting said flattened tube for forming cartonblanks from the said lengths.
 3. A method as claimed in claim 1 in whichthe step of adhering the edges of the offset plies and the edges of thecore plies comprises adhering the inner surface of the edge of each faceply which projects beyond the core ply to the outer surface of the edgeof said face ply beyond which the core ply extends.
 4. A method asclaimed in claim 3 in which the corrugations at one edge of the core plyare interfitted with the corrugations at the other edge of the core ply.5. A method as claimed in claim 3 in which the corrugation at one edgeof the core ply is abutted against the corrugation at the other edge ofthe core ply.
 6. An apparatus for producing flat folded corrugatedcontainer blanks, comprising: a corrugating means for receiving a stripof flat core ply stock and forming in it corrugations extendinglongitudinally of the strip to form a strip of core ply; a support platefor receiving the strip of core ply; adhesive applicator means betweenthe corrugating means and the support plate for applying adhesive to thetop portions of the corrugations on both sides of the core ply; face plyfeed means adjacent the support plate for feeding a face ply against thelower surface of the core ply as it moves onto the suppOrt plate and forfeeding a face ply against the upper surface of the core ply as it movesonto the support plate to form a strip of corrugated cardboard, saidface ply feed means including edge detectors for detecting andcontrolling the direction of feed of the face plys for offsetting one ofthe face plys in one lateral direction relative to the core ply andoffsetting the other face ply in the opposite lateral direction relativeto the core ply; a mandrel extending in the same direction as saidsupport plate from the end of the support plate opposite the endadjacent to the corrugating means, said mandrel having a generallyrectangular cross section tubular part adjacent the support plate, aflat part at the end remote from the support plate, and an intermediatepart tapering gradually from the tubular part to the flattened part; anadhesive applicator adjacent the tubular part of the mandrel forapplying adhesive to the edges of the corrugated cardboard; corrugatedcardboard bending means along said tubular part of said mandrel forbending the strip of cardboard longitudinally around said mandrel andoverlapping the edges thereof for forming a tube of the corrugatedcardboard; cardboard pressing means along said mandrel for pressing theoverlapped edges of the cardboard; feed means along said mandrel forengaging said tube of corrugated cardboard and feeding it along saidmandrel; and transverse cutting means at the end of said mandrel forcutting lengths of said tube of corrugated cardboard from said tube. 7.An apparatus as claimed in claim 6 further comprising slitting means andcreasing means along said support means between said face ply feedingmeans and said mandrel for slitting the cardboard and creasing it forproviding flaps and fold lines in the finished blanks.
 8. An apparatusas claimed in claim 6 in which said corrugating means comprises aplurality of groups of balls the size of the corrugations to be formedin the core ply stock, each group of balls having a plurality of upperside by side rows of balls and lower side by side rows of balls, therows extending in an inwardly converging direction along the directionof length of the core ply, the rows of balls in the upper row beingpositioned between the rows of balls in the lower row, the groups ofballs being spaced in the direction of length of the core stock and therows in the successive groups being closer together and the upper ballsin the successive groups being closer to the lower balls with the ballsin the last successive group being substantially side by side.